112 research outputs found
Matching the BPS Spectra of Heterotic - Type I - Type I' Strings
We give a detailed discussion of the matching of the BPS states of heterotic,
type I and type I' theories in d=9 for general backgrounds. This allows us to
explicitly identify these (composite) brane states in the type I' theory that
lead to gauge symmetry enhancement at critical points in moduli space. An
example is the enhancement of to .Comment: 11 pages; minor typos in eq. (3), (4) and on page 9 have been
corrected; two footnotes taking into account additional references have been
added; version to appear in Physics Letters
Implications of non-universality of soft terms in supersymmetric grand unified theories
Most discussions of supersymmetric grand unified theories assume universality
of the soft supersymmetry breaking terms at the grand scale. We point out that
the behaviour of these theories might change significantly in the presence of
non--universal soft terms. Particularly in SO(10)--like models with a large
value of tan we observe a decisive change of predictions, allowing the
presence of relatively light gauginos as well as small supersymmetric
corrections to the b--quark mass. Some results remain rather stable, including
the -- correlation. Models with small tan seem to be less
affected by non--universality which mainly leads to the new possibility of
small (i.e. the squark and slepton soft mass parameter), excluded in
the universal case.Comment: 15 pages (Latex) plus 5 figures (uuencoded postscript file). TUM-HEP
201/9
Predictions for Higgs and SUSY spectra from SO(10) Yukawa Unification with mu > 0
We use Yukawa unification to constrain SUSY parameter space. We
find a narrow region survives for (suggested by \bsgam and the
anomalous magnetic moment of the muon) with , , \gev and \gev. Demanding Yukawa unification thus makes definite predictions for
Higgs and sparticle masses.Comment: 10 pages, 3 figures, revised version to be published in PR
Probing EWSB Naturalness in Unified SUSY Models with Dark Matter
We have studied Electroweak Symmetry Breaking (EWSB) fine-tuning in the
context of two unified Supersymmetry scenarios: the Constrained Minimal
Supersymmetric Model (CMSSM) and models with Non-Universal Higgs Masses (NUHM),
in light of current and upcoming direct detection dark matter experiments. We
consider both those models that satisfy a one-sided bound on the relic density
of neutralinos, , and also the subset that satisfy
the two-sided bound in which the relic density is within the 2 sigma best fit
of WMAP7 + BAO + H0 data. We find that current direct detection searches for
dark matter probe the least fine-tuned regions of parameter-space, or
equivalently those of lowest Higgs mass parameter , and will tend to probe
progressively more and more fine-tuned models, though the trend is more
pronounced in the CMSSM than in the NUHM. Additionally, we examine several
subsets of model points, categorized by common mass hierarchies; M_{\chi_0}
\sim M_{\chi^\pm}, M_{\chi_0} \sim M_{\stau}, M_{\chi_0} \sim M_{\stop_1}, the
light and heavy Higgs poles, and any additional models classified as "other";
the relevance of these mass hierarchies is their connection to the preferred
neutralino annihilation channel that determines the relic abundance. For each
of these subsets of models we investigated the degree of fine-tuning and
discoverability in current and next generation direct detection experiments.Comment: 26 pages, 10 figures. v2: references added. v3: matches published
versio
5d quivers and their AdS(6) duals
We consider an infinite class of 5d supersymmetric gauge theories involving
products of symplectic and unitary groups that arise from D4-branes at orbifold
singularities in Type I' string theory. The theories are argued to be dual to
warped AdS(6)x S4/Zn backgrounds in massive Type IIA supergravity. In
particular, this demonstrates the existence of supersymmetric 5d fixed points
of quiver type. We analyze the spectrum of gauge fields and charged states in
the supergravity dual, and find a precise agreement with the symmetries and
charged operators in the quiver theories. We also comment on other brane
objects in the supergravity dual and their interpretation in the field
theories.Comment: 29 pages, 15 figure
Sparticle Mass Spectra from SO(10) Grand Unified Models with Yukawa Coupling Unification
We examine the spectrum of superparticles obtained from the minimal SO(10)
grand unified model, where it is assumed the gauge symmetry breaking yields the
Minimal Supersymmetric Standard Model (MSSM) as the effective theory at
GeV. In this model, unification of Yukawa
couplings implies a value of . At such high values of
, assuming universality of scalar masses, the usual mechanism of
radiative electroweak symmetry breaking breaks down. We show that a set of weak
scale sparticle masses consistent with radiative electroweak symmetry breaking
can be generated by imposing non-universal GUT scale scalar masses consistent
with universality within SO(10) plus extra -term contributions associated
with the reduction in rank of the gauge symmetry group when SO(10)
spontaneously breaks to . We comment upon the
consequences of the sparticle mass spectrum for collider searches for
supersymmetry. One implication of SO(10) unification is that the light bottom
squark can be by far the lightest of the squarks. This motivates a dedicated
search for bottom squark pair production at and colliders.Comment: 12 page REVTEX file including 3 PS figures; revised manuscript
includes minor changes to coincide with published versio
Compatibility of the new DAMA/NaI data on an annual modulation effect in WIMP direct search with a relic neutralino in supergravity schemes
Recent results of the DAMA/NaI experiment for WIMP direct detection point to
a possible annual modulation effect in the detection rate. We show that these
results, when interpreted in terms of a relic neutralino, are compatible with
supergravity models. Together with the universal SUGRA scheme, we also consider
SUGRA models where the unification condition in the Higgs mass parameters at
GUT scale is relaxed.Comment: 10 pages, ReVTeX, 13 figures (included as PS files
Non-Universal Soft SUSY Breaking and Dark Matter
An analysis is given of the effects of non-universal soft SUSY breaking
masses in the Higgs sector and in the third generation squark sector, and it is
shown that they are highly coupled. Analytic expressions are obtained for their
effects on the parameters and on the third generation squark masses.
Non-universality effects on dark matter event rates in neutralino-nucleus
scattering are analysed. It is found that the effects are maximal in the range
~GeV where the relic density is governed by the Z and
Higgs poles. In this range the minimum event rates can be increased or
decreased by factors of O(10) depending on the sign of non-universality. Above
this range Landau pole effects arising from the heavy top mass tend to suppress
the non-universality effects. The effect of more precise measurements of
cosmological parameters on event rates, which is expected to occur in the next
round of COBE like sattelite experiments, is also investigated. Implications
for the analysis for dark matter searches are discussed.Comment: 28 pages, latex, and 7 fig
Extended Tree-Level Gauge Mediation
Tree-level gauge mediation (TGM) is a scenario of SUSY breaking in which the
tree-level exchange of heavy (possibly GUT) vector fields generates
flavor-universal sfermion masses. In this work we extend this framework to the
case of E_6 that is the natural extension of the minimal case studied so far.
Despite the number of possible E_6 subgroups containing G_SM is large (we list
all rank 6 subgroups), there are only three different cases corresponding to
the number of vector messengers. As a robust prediction we find that sfermion
masses are SU(5) invariant at the GUT scale, even if the gauge group does not
contain SU(5). If SUSY breaking is mediated purely by the U(1) generator that
commutes with SO(10) we obtain universal sfermion masses and thus can derive
the CMSSM boundary conditions in a novel scenario.Comment: 22 pages, 2 figures, 3 table
Yukawa Unification as a Window into the Soft Supersymmetry Breaking Lagrangian
We study Yukawa unification, including the effects of a physical neutrino
mass consistent with the Superkamiokande observations, in a string/-brane
inspired Pati-Salam model which allows the most general non-universal scalar
and gaugino masses, including the usual -term contributions which arise in
SO(10). We investigate how the tight constraints from rare decays such as and can provide information about the
family dependent supersymmetry breaking soft Lagrangian, for example the
trilinears associated with the second and third family. Many of our results
also apply to SO(10) to which the model approximately reduces in a limiting
case. In both models we find that Yukawa unification is perfectly viable
providing the non-universal soft masses have particular patterns. In this sense
Yukawa unification acts as a window into the soft supersymmetry breaking
Lagrangian.Comment: References added. 82 pages, 57 figures, Late
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